Cutter for well drills



June 7, 1960 Ly/e Z. Pay/7e INVENTOR.

ATTORNEY June 7, 1960 L. L. PAYNE 2,939,684

CUTTER FOR WELL DRILLS Filed March 22, 1957 2 Sheets-Sheet 2 -II mill/7.

Zy/e Z. Pay/7e INVENTOR. 311%AM ATTORNEY United States Patent 21,939,684CU'ITER FOR WELL DRILLS Lyle L. Payne, Houston, Tex., assignor to HughesT Company, Houston, Tex., a corporation of Delaware Filed Mar. '22,1957, Ser. No. 647,788

7 Claims. (Cl. 255-349 ,The base metal of the cutter body isconventionally tough and strong but is notsufliciently abrasionresistant to provide adequate distintegrating action upon the wall ofthe well bore to maintain full gage of the bore thoughout the usefullife ofthe remainderof the cutter. To overcome this dimculty, it hasbeen pr posed toIsuperpo e a layer of wear resistant metal upon he outerends of the heel teeth and the adjacent metal of thecutter uch layercomprising a carbide, such as paiticles of u asten carbide, ecuredinplace by a matrix of suitabl m t l such as mild steel applied by atorch so that the m rix me al wets the s rface of the base met l of thcutter and the carbi es t us providing an effective interbond to holdthe particles in Place to serve their intended purpose.

To facilitate application ofthe layerof wear resistant metal upon thecutter body it has also been proposed'to provide radially extending ribsof the base metal on the gage surface of the cutter and 'to'then applywear resistant material and matrix metal bonded to the base metal and ofa depth that the gage surface is flush with the crests of the ribs.

Such prior art structures have-been found to be inadequate, especiallywhen drilling hard rock formations, to assure maintenance of gage, ordiameter of the bore hole,

I throughout the useful life of the remainder of the cutter.

Thus, for some time prior to withdrawing and replacing the bit a taperedhole is being drilled; Then the'succeeding bit, which is of full gage,must ream the tapered hole before it reaches bottom. This reamingoperation is time consuming and also effects destructive action upon thenew hit and especially upon the gage cutting portion thereof whereby theuseful life of the bit is'materially reduced. in some cases the new hitis rendered unfit for advancing the bore and another new bit is requiredbefore further drilling is resumed.

The principal 'difiic =ty arises from initial chipping or breaking awayof the wear resistantmaterial at the outermost portion of the gagesurface. fiance the composite wear resistant material and its matrixmetal are relatively brittle the chipping action is progressive thuscausing socalled heeling over or reduction of gage beginning at thepoint of maximum diameter of the roller cutter and ultimately leading tocomplete dest uction of the gage surface. This of course gives rise tounder gage hole as well as early failure of the cutter.

It is therefore the primary object of the invention to provide astructure'whi'ch' minimizes the difficulties to which reference has justbeen made.

The invention comprehends the provision of a gage cutter 1 and integralwith the heel teeth 5 "ice fac mpr sing areal deposits of wear esistantmaterial k d p by rib f ba e m al of he cu ter body extendingtransversely of the direction of the principal destructive forces towhich the gage cutting portion of the cutter is subjected when in normaluse. Such forces are directed substantially radially inwardly along thegage surface. i

An ther obj ct is to p o d a sag cut ng structur which may be em odi din ny typ of rollin cu ter havin a sag cu ting fun i n- Still another anmore specific object is. t provide a rolling cutter having bottom.cutting elements wh ch cu th ou r bot om po ion. of. the we bore nd aWeb inter onne ting the outer e ds ot said elem n ..the ou surface ofaid web e ng a sage urface having spaced an ular ri s. of the a metal othe cutter andwea r is an materiai fill ng the p c e ween suc es iveribs and bonded thereto.

T ese and. her o je ts; w be mo e ully pparen f m th f wing r p n and heaccompanying drawings in which; 1 I

Fig. 1 is a side elevational view of a cone type cutter em yin th n entig-2 s a iew showing in e e ati n the sage f he rcut a p ion f th ea istnt, material being.

broken away to enhance the showing of the structure;

Fig. 3 is a sectional view, taken'on line 3-3 Fig, 2;

Fig.4 is a sectional view ta ken'on line 4 4- in Fig; 2; Fig; 5 is aside elevational'view of a side roller type of cutter embodying theinvention. Theinvention as shown in Figs. 1 and 2 comprisesa cone typecutter jl contoured internally as shown generally at 2 (Fig. 2) toreceive bearing elements and a mounting shaft (not shown) upon which thecutter revolves as is well lgnown in the art. The cutter body 1 issymmetrical about its axis of rotation and is provided on'its arcuatebottom cutting portion 3 with rows of cutter teeth 4 and 5 the latter ofwhich are known as heel teeth and an individual tooth is referenced at6. The base metal of the cutter 1 and the teeth thereon is an' alloysteel and may be fortified against abrasion by suitable heat treatmentor selective placement ofwear resistant material especially upon theflanks or ends of the teeth. Since such specific structure is relativelyconventional and is not specifically concerned in the present invention,a general reference only is made thereto. The gage surface or gagecutting portion lti'compr ses an intermpted web 11 which is'a componentpart of the at their outer ends. it is to be noted that the gage surface510 is generally conical, or frusto-conical, and intersects the bottomcutting portion 3 at 12, the maximum diameter of the cutter. It is atthis point, which rolls at the juncture of the bottom and the side wallof a well bore that the most excessive stresses and abrading action areincurred. Because of the rolling action of the cutter the stresses aredirected substantially radially inwardly of the cutter and initiatebreakdown of gage structure at the point 12.

Reference to the web 11 as interrupted means that :at

intervals the web is cut away between successive h'eel teeth 6 as shownby the notches 13. Preferably theflside walls 14 of each of thesenotches follow the flanks of the two teeth inwardly therefrom. Also thegage snrface is recessed inwardly from each of the notches 13 .as shownat 15 This notching and recess-ing enhances ventilation of the gagestructure to minimize grinding action upon formation material which hasbeen severed and which tends to wedge between the gage surface and thewall of the hole being drilled. This yentilation is further enhanced byradial grooves 16 in the gage surfaceQ-Wwhich grooves are approximatelyor slightly deeper than the wear resistant portion of the gagesurfacelt).

Patented June 7, 1960' ber which depends upon the amount of ventilationnecessary for the type of formation being drilled.- Especially if thereis an odd number of heel teeth 6 in the row 5, the

*number of teeth interconnected by uninterrupted portions of the web11-will vary.

An important aspect of the invention resides in that portion of the gagesurface 10 intermediate the notches 13 and the grooves 16. As best seenin Figs. 2 and 3 this feature of construction is effected by cutting aplurality of concentric grooves 20, 21, and 22 in the outer face of theweb 11 leaving upstanding concentric ribs 23, 24, and 25 of a heightthat their crests lie upon, or substantially upon, the finished gagesurface 10 of the cutter. v

A body of wear resistant metal 216 is then deposited in each of thegroove segments and bonded to the bottoms of the segments and the sidewalls of the ribs 23, 24, and

"25 as best seen in Fig. 4. Preferably, though not limited thereto, thebody of metal 26 comprises particles of a carbide, such as tungstencarbide, interbonded with each other and with the adjacent base metal ofthe cutter 1 by means of a suitable matrix metal such as mild steel or asuitable alloy.

It is here noted that the-outermost groove 20 extends to the point 12 ofthe cutter and that hence the outermost body of metal 26 engages thebottom of the well bore at .the juncture of the bottom with the sidewall of the bore. While it is uncertain as to the reason for thesuperior qualities of the cutter thus far described it is believed thatthe rib 23 of basemetal of the cutter serves to stabilize the adjacentbody of wear resistant metal against chipping or breaking away. In anyevent if excessive weight is applied and chipping or breaking awayoccurs suchchipping or breaking extends only to the adjacent rib of basemetal and does not extend a major portion or all the way across the gagecutting portion 10.

drills, a series of substantially longitudinally crested heel Fig. 5 issimilar to Fig. 1 but shows a rolling cutter of the type usable as sidecutters on cross roller bits or as cutters on reaming bits to maintaingageof the hole cut thereby. Like parts are identified by like butprimed reference characters.

By way of summary it is pointed out that the bottom cutting portion andthe gage cutting portion 10 of the cutter 1 are referred to as generallyconical. While generally conical, or frusto-conical, surfaces areillustrated and described it is to be understood that reference is hadproved roller cutter for well drills and more particularly 7 a cutterhaving as a component part a gage cutting structure which facilitatesthe maintenance of gage throughout the usefullife of the cutter.

The invention claimed is:

1. A rotary drill cutter comprising a frusto-conical body having aseries of circumferentially spaced longitudinally extending heel teethon one end thereof, a circumferential web joining the outer ends of atleast some of said teeth andv forming an outwardly facing frusto conicalgage surface, a plurality of concentric grooves in the face of said web,and a wear resistant material filling said grooves and bonded to thesides and bottoms thereof.

2. A rotary drill cutter comprising a frusto-conical body having aseries of circumferentially spaced longimaterial filling said .4 outerface, a plurality of concentric grooves in said-outer face of the webtransecting said radially extending grooves, and a wear resistantmaterial filling each of said concentric grooves and bonded to the sidesand bottoms thereof.

3. In an approximately conical shaped cutter for well drills, a seriesof substantially" longitudinally crested heel teeth thereon, acircumferential web joining the outer ends of said teeth and forming anoutwardly facing frustoconical gage surface, said web having a crestextending to approximately the same height as said heel teeth, aplurality of concentric grooves in the face of said web, and a wearresistant material filling said grooves and bonded to the base metal ofthe cutter.

4. In an approximately conical shaped cutter for well drills, a seriesof substantially longitudinally crested heel teeth thereon, acircumferential web joining the outer ends of said teeth and forming anoutwardly facing frustoconical gage surface, said web having a crestextending to approximately the same height as said heel teeth, aplurality of concentric grooves in the face of said web, the outermostof said grooves extending to the crest of the web, and a wearresistant'material filling said grooves and bonded to the base metal ofthe cutter.

5. In an approximately conical shaped cutter for'well :drills, a seriesof substantially longitudinally crested heel teeth thereon, acircumferential web joining the outer ends of said teeth and forming anoutwardly facing frustoconical gage surface, said web being cut awaybetween successive heel teeth at spaced intervals whereby the teeth areinterconnected in groups, a plurality of concentric grooves in the faceof said web, and a wear resistant grooves and bonded to the base metalof the cutter. i

6. In an approximately conical shaped cutter for well teeth thereon, acircumferential Web joining the outer ends of said teeth and forming anoutwardly facing frustoconical gage surface, said web having: its crestextending to substantially the height of said heel teeth, said web beingcut away between successive heel teeth at spaced intervals whereby theteeth are interconnected in groups, a plurality of concentric grooves inthe face of said web, the outermost of said grooves extending to thecrest of the web, and a wear resistant material filling each of saidgrooves and bonded to the base metal of the cutter.

7. A rotary drill cutter for earth boring drills comprising a bodyhaving a pair of integral oppositely extending frusto-conical portionssymmetrical about a common axis of rotation and having a common baseintermediate the ends of the cutter body, one of said frusto-conicalportions having a series of circumferentially spaced, longitudinallyextending heel teeth thereon, the. other of said frusto-conical portionsforming a gage surface, a web integral with said frusto-conical portionslocated at the common base, connected to said heel teeth and forming anextension of the gage surface, a plurality of concentric grooves in saidgage surface and web, and a wear resistant material filling said groovesand bonded to the cutter Morlan Dec. 18,

